It has been a long tradition that highly skilled perfumers carefully select fragrance materials to blend into a composition with the goal of achieving an overall specific fragrance profile of strength and character. In so doing, they need to bear in mind differences in the individual character and volatility of the fragrance materials that are the components of the full fragrance. Conventional perfuming compositions have fragrance profile characterized by a high amount of the low volatile fragrance materials and lower amounts of the volatile fragrance materials. The low volatile fragrance materials are known as “base notes”, while the volatile fragrance materials can be further divided into high volatile fragrance materials, identified as “top or head notes”, and medium volatile fragrance materials, identified as “middle or heart notes”.
The top notes tend to smell citrusy, green, light, fresh, and comprise typically from about 0.1 wt % to 40 wt % relative to the total weight of the perfume formulation. Top notes tend to evaporate quickly due to their high volatility and are characterized by vapor pressure >0.1 Torr at 25° C. (Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (© 1994-2013 ACD/Labs)). Typically, perfumers use top notes to deliver the initial impression of the composition but do not rely on them to contribute much to its overall fragrance profile over time after application.
Middle or heart notes make up from about 0.1 wt % to about 40 wt % relative to the total weight of the perfume formulation. Generally, they become dominant to the untrained nose from several minutes after application and can last up to a few hours afterwards. Middle notes are associated with floral aromas (e.g., jasmin, rose), fruity, marine or spicy aromas and have an intermediate volatity in the vapor pressure range of 0.001 to 0.1 Torr at 25° C.
Base or bottom notes can exist at >30 wt % relative to the total weight of the perfume formulation. They are characterized as animalic, woody, sweet, amber or musky, not being very volatile and having a vapor pressure <0.001 Torr at 25° C. Typically, they are not perceived as dominant until several hours after the application of the perfume or during “dry-down”. Base notes are relied upon to improve the strength of the overall fragrance profile over time and replace the heart notes when these are declining, The consequence of using base notes at high levels is that they impart particular odour characters, such as for example, musky, woody, ambery, warm and sweet, which overpower and dominate the fragrance character over time. Some of these base notes have become such common materials (e.g., hedione, galaxolide, etc.) that many fragrance dry-downs appear repetitive, boring, non-memorable and un-interesting to consumers. However, if base notes are reduced or excluded then the fragrance strength weakens over time and does not last for a sufficient duration.
To date, due to the volatility of the fragrance materials, the possible types of fragrance profiles or characters have been somewhat limited. A common complaint by consumers is that middle notes tend to fade too quickly after application of the composition and that the character of the middle notes are undesirably altered by the presence of large amounts of the base notes during the period known as the “dry-down” phase.
Thus, it is desirable to have a composition which retains a significant portion of its initial fragrance character over time, hence, the floral, fruity or spicy characters of the ‘heart notes’ are perceived for many hours It is also desirable that the fragrance strength of the composition remains noticeable to the consumer over longer periods of time. It is further desirable to be able to create new to the world fragrance profiles wherein one, or several, well-recognized heart note characters, are maintained over time.
It is therefore a challenge to formulate a composition having improved longevity of the fragrance character, without having the fragrance character substantially altered over time by the presence of the base notes in the composition. One approach for addressing the challenge has been to formulate with higher proportions of perfume raw materials with a low volatility and which are therefore more substantive on the substrate. However, as discussed above, this restricts the type of fragrance profile that can be achieved over time.
Another approach, as disclosed in U.S. Pat. No. 4,264,478 (Amerchol Corp.), has been to use a non-odorous material, such as an alkoxylated methyl glucoside, as a modulator to extend the longevity of the perfume raw materials, which are normally too volatile to last for very long. However, U.S. Pat. No. '478 simply teaches the addition of the modulator to an existing fragrance composition with a traditional construction of high levels of base note materials. As such, the resultant overall effect on the fragrance profile of the composition would be to make the whole fragrance weaker because the impact of the modulator on the more volatile fragrance materials cannot be noticed due to the presence of excessive levels of the base notes in the composition.
Similarly, Moshel, et al., Perfumer & Flavorist, Vol. 7, pp. 41-47, 1982, teaches that alkoxylated methyl glucosides function as a “fixative” and bind to individual perfume raw materials for improving the longevity of a particular perfume raw material. Moshel, et al., shows that the fixative's ability to improve the longevity for any particular perfume raw material will depend on its boiling point. However, Moshel, et al., does not disclose or suggest how to formulate with the fixative for a full fragrance composition, which incorporates multiple perfume raw materials, so that the fragrance strength is maintained and the character of the middle notes is perceived as dominant after many hours.
As such the prior art teachings still have limitations, and do not adequately teach how to provide a composition wherein the prolonged fragrance profile has sufficient strength to be noticeable and remains distinctive in character over time. Therefore, there remains a need for a composition that is perceived by the consumer over long duration after application. There is also a need for a composition which exhibits enhanced intensity of the fragrance profile over time, so that the volatile fragrance materials remains significantly consistent from its initial impression to the end. It is desirable that the compositions are relevant to fragrances derived from volatile fragrance materials having a vapor pressure ≧0.001 Torr at 25° C.